The man who scored seven times in the previous qualifying campaign arrived with 18 minutes to go at Windsor Park, with his country only 1-0 up, and he scored twice and set up another for Jamie Ward as O'Neill's team ran out 4-0 winners in their World Cup qualifier.

Lafferty is unwanted by the Canaries and failed to push through a deadline-day loan move away from Carrow Road, meaning O'Neill has a player whose depleted fitness levels were evident when he started and faded in last month's 0-0 draw with the Czech Republic.

"My situation with Kyle's fitness is simple: do I play him for 50 minutes and take him off because he's not played many minutes over the past year? Or do we get more out of him bringing him into the game later on?" O'Neill said.

"The last 20 minutes, maybe the game's stretched a bit, the opposition are tired and there's opportunities there for him. He took his chance when he came on. I think he understands the situation. It's very difficult to walk into international football and just play if you've not played for your club.

"He's not starting because he's not been played. We've had a situation in the sense Kyle's played 45 minutes of football in a month.

"Going back to the Czech Republic, we ran out of gas in the second half because we had too many players that hadn't played too many minutes for their club.

"When I look at Kyle's situation, it's about where we can maximise his use to the team and (Saturday night) was the best example of doing that. He came in when it was stretched, we needed that second goal. He came on and did it fairly quickly.

"(On Saturday night) he proved what a huge asset he is to the team. We need him more match-ready than he is and I think he knows that."

The tall striker came on with Steven Davis' penalty the only contribution to the scoresheet, but the home side were eventually able to claim a comprehensive victory having amassed over 30 shots on Aldo Simoncini's goal in the first international hosted at their fully refurbished stadium.

They were helped by Mirko Palazzi's dismissal early in the second half, a second yellow card hardly helping the cause for a country that have never won a competitive contest, and it gave the hosts a rare opportunity to run up the score.

It was also a timely confidence booster ahead of Tuesday's clash with Germany, when it is unlikely to be the green shirts showcasing their attacking verve.

"The most positive thing is we won the game, we won it comfortably and we go to Germany and have a game with everything to gain," O'Neill added. "Anything we can take will be a huge bonus."

San Marino would have viewed a slender defeat as a victory of sorts, and the microstate may have produced that outcome had Palazzi kept his discipline instead of needlessly impeding Michael McGovern as he tried to throw out.

"We had a very good match but the red card in the second half conditioned our match," boss Pierangelo Manzaroli said.

"(When it was) 10 against 11 it was very, very hard. It's very, very difficult but I'm very happy and proud of the game played by the players."